The states of New York, California, Washington, Illinois, Massachusetts, Ohio, and Pennsylvania have joined the DOJ's antitrust lawsuit against AT&T, T-Mobile USA and T-Mobile parent Deutsche Telekom, the DOJ said Friday.

The deal, which would create the largest mobile carrier in the U.S., would significantly reduce competition, jack up prices and stifle innovation, the DOJ said in its lawsuit, filed Aug. 31. The DOJ pointed to T-Mobile USA's role as a low-cost competitor to the three other nationwide mobile carriers as a reason to block the deal.

AT&T officials have said they will fight the lawsuit. The company has argued the merger will allow it build out mobile broadband service to more U.S. residents and will help it improve quality of service.

The company continues to seek an expedited hearing on the DOJ's complaint, an AT&T spokeswoman said. "On a parallel path, we have been and remain interested in a solution that addresses the DOJ's issues with the T-Mobile merger," she said.

It is "not unusual" for state attorneys general to participate in DOJ merger reviews, the spokeswoman added. "At the same time, we appreciate that 11 state attorneys general and hundreds of other local, state and federal officials are publicly supportive of our merger," she said.

The Computer and Communications Industry Association, a tech trade group, and Public Knowledge, a digital rights group, applauded the states for joining the lawsuit.

The attorneys general have "wisely weeded through the promises versus the reality of AT&T's takeover bid, and are taking steps to protect their states from the higher prices that come when an industry no longer has competition," Ed Black, CCIA's president and CEO, said in a statement.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is grant_gross@idg.com.